Aaron R Casha1, Alexander Manché2, Ruben Gatt3, Wiktor Wolak4, Krzysztof Dudek4, Marilyn Gauci5, Pierre Schembri-Wismayer5, Marie-Therese Camilleri-Podesta5, Joseph N Grima3. 1. Department of Cardiac Services, Mater Dei Hospital, Msida, Malta Faculty of Medicine, Department of Anatomy, University of Malta, Msida, Malta aaron.casha@um.edu.mt. 2. Department of Cardiac Services, Mater Dei Hospital, Msida, Malta. 3. Faculty of Science, Metamaterials Unit, University of Malta, Msida, Malta. 4. Department of Physics and Astronomy, Uniwersytet Zielonogórski, Zielona Góra, Poland. 5. Faculty of Medicine, Department of Anatomy, University of Malta, Msida, Malta.
Abstract
OBJECTIVES: Primary spontaneous pneumothorax has long been explained as being without apparent cause. This paper deals with the effect of chest wall shape and explains how this may lead to the pathogenesis of primary spontaneous pneumothorax. METHODS: Rib cage measurements were taken from chest radiographs in 12 male pneumothorax patients and 12 age-matched controls. Another group of 15 consecutive male thoracic computerised tomography (CT) were investigated using paramedian coronal and sagittal CT reconstructions to assess apical lung shape. A finite element analysis (FEA) model of a lung apex was constructed, including indentations for the first rib guided by CT scan data, to assess pleural stress. This model was tested using different anteroposterior diameter ratios, producing a range of thoracic indexes. RESULTS: The pneumothorax patients had a taller chest (P = 0.03), wider transversely (P = 0.009) and flatter (P = 0.03) when compared with controls, resulting in a low thoracic index. Prominent rib indentations were found anteriorly and posteriorly on the lung surface, especially on the first rib on CT. FEA of the lung revealed significantly higher stress (×5-×10) in the apex than in the rest of the lung. This was accentuated (×4) in low thoracic index chests, resulting in 20-fold higher stress levels in their apex. CONCLUSIONS: The FEA model demonstrates a 20-fold increase in pleural stress in the apex of chests with low thoracic index typical of spontaneous pneumothorax patients. Mild changes in thoracic index, as occurring in females or with aging, reduce pleural stress. Spontaneous pneumothorax occurring in young male adults may have a biomechanical cause.
OBJECTIVES: Primary spontaneous pneumothorax has long been explained as being without apparent cause. This paper deals with the effect of chest wall shape and explains how this may lead to the pathogenesis of primary spontaneous pneumothorax. METHODS: Rib cage measurements were taken from chest radiographs in 12 male pneumothorax patients and 12 age-matched controls. Another group of 15 consecutive male thoracic computerised tomography (CT) were investigated using paramedian coronal and sagittal CT reconstructions to assess apical lung shape. A finite element analysis (FEA) model of a lung apex was constructed, including indentations for the first rib guided by CT scan data, to assess pleural stress. This model was tested using different anteroposterior diameter ratios, producing a range of thoracic indexes. RESULTS: The pneumothorax patients had a taller chest (P = 0.03), wider transversely (P = 0.009) and flatter (P = 0.03) when compared with controls, resulting in a low thoracic index. Prominent rib indentations were found anteriorly and posteriorly on the lung surface, especially on the first rib on CT. FEA of the lung revealed significantly higher stress (×5-×10) in the apex than in the rest of the lung. This was accentuated (×4) in low thoracic index chests, resulting in 20-fold higher stress levels in their apex. CONCLUSIONS: The FEA model demonstrates a 20-fold increase in pleural stress in the apex of chests with low thoracic index typical of spontaneous pneumothorax patients. Mild changes in thoracic index, as occurring in females or with aging, reduce pleural stress. Spontaneous pneumothorax occurring in young male adults may have a biomechanical cause.
Authors: Aaron R Casha; Luca Bertolaccini; Liberato Camilleri; Alexander Manche; Marilyn Gauci; Gor Melikyan; Ruben Gatt; Krzysztof Dudek; Piergiorgio Solli; Joseph N Grima Journal: J Thorac Dis Date: 2018-06 Impact factor: 2.895
Authors: Dominik Herzog; Alexander Poellinger; Felix Doellinger; Dirk Schuermann; Bettina Temmesfeld-Wollbrueck; Vera Froeling; Nils F Schreiter; Konrad Neumann; Stefan Hippenstiel; Norbert Suttorp; Ralf-Harto Hubner Journal: PLoS One Date: 2015-05-26 Impact factor: 3.240